On the basis of experience of more than 5,000 cases (since 1974), the authors describe the tomodensitometric appearences of non-surgical cerebral haemorrhages, together with the correlation between values of radiodensity and histological lesions. They emphasise the chronological changes which take place in the tomodensitometric appearance of the lesions and the possibility of easy repeated studies. Such studies, in combination with observation of the clinical course, have enabled the authors to give the scanner an important place in decisions to proceed to surgery. The authors stress the superiority of the scanner over invasive techniques used to explore such patients, from both an ethical as well as a diagnostic standpoint. They consider that it will be of value in the future in experimental studies aimed at elucidating the physiopathology of these lesions.